The prior patent describes an extremely advantageous technique for mechanically amplifying sounds within a frequency range of interest in a stethoscope, wherein a resonant cavity is connected to the stethoscope's sound passage. The resonant cavity is vented to the atmosphere, most conveniently in the form of a flexible tube having its end completely opened. The length of the tube from the pick-up head to the vent determines the frequency range of its amplification. Two, or even more, resonant cavities of different lengths can be utilized along with a manual control valve connecting them to the sound passage, so that the frequency range of amplification may be selected by the user of the stethoscope for listening to different functions of a patient's heart and lungs.
It is a primary object of the present invention to further improve the characteristics of such resonant cavity sound amplification in stethoscopes.
It is also an object of this invention to provide an improved sound pick-up head construction.